Electric hand appliances, particularly toothbrushes



M. MORET May 4, 1965 ELECTRIC HAND APPLIANCES, PARTICULARLY TOOTHBRUSHESFiled April 25, 1963 3 Sheets-Sheet l INVENTOR Michel More? Y fi M W aATTORN EYS M. MORET May 4, 1965 ELECTRIC HAND APPLIANCES, PARTICULARLYTOOT HBRUSHES 3 Sheets-Sheet 2 Filed April 25, 1963 INVENTOR MichelMoret 4 W 2 116. 7

ATTORNEYS FIG. 3

May 4, 1965 M. MORET 3,181,188

ELECTRIC HAND APPLIANCES, PARTICULARLY TOOTHBRUSHES Filed April 25, 1963s Shee ts-Sheet 5 INVENTOR Michel Moref 42 ATTORNEYS United StatesPatent M 351815.88 ELECTRIC HAND APPLKANCES, PARTECU- LARLY TGGTHBRUSHESMichel Moret, Geneva, Switzerland, assiguor to Etahlisse= ments AEUP,Vaduz, Liechtenstein, a firm of Liechtenstein Filed Apr. 25, B63, SeLNb.275,646 Claims priority, application Switzerland, Apr. 27, 1962,

5,087/62 7 Claims. (til. 15-22) This invention relates toelectrically-operated hand appliances forcorporal care, and especiallyto electrically operated toothbrushes. The invention is particularlydirected to the provision of an electrically safe appliance of thischaracter incorporating an electric switch therein.

It is well known that the use of elecrical appliances is very dangerouswhen the device that should enclose operative elements in a fluidtightmanner at the voltage of their control switch happens to failunexpectedly, and a conducting liquid, particularly water, enters thecasing provided for such elements. This danger is particularly great inhygienic appliances, either because the user employs them when his bodyis partily immersed in the water or is not sufiiciently insulated fromthe ground, for instance when using in a bathroom, or else because theseappliances are expressly designed to operate in the presence of aconducting liquid medium, particularly in the case of electricaltoothbrushes.

Electrically-operated toothbrushes are now known including a casingforming a handle, a shaft extending through one end of the casing forcarrying a toothbrush head, and electrical means mounted within thecasing for oscillating the shaft. One particular type is disclosed inUS. Patent No. 2,917,758, issued December 22, 1959 to Held et al. Inthis toothbrush the shaft is rotationally oscillated so as to impart acorresponding motion to a toothbrush head attached thereto and brush theteeth in the lengthwise direction thereof. Other types are known inwhich a longitudinal oscillation is imparted to the shaft. By usingdifferent types of heads, the appliance can be used for other types ofcorporal care, such as massage, beauty treatment, etc.

When such appliances are arranged to be connected to an external powersupply such as the power mains, it is highly important to providecomplete protection against the danger of an electric shock. They arecommonly employed in the bathroom where the appliance or the hands ofthe user may be wet, so that even small amounts of electrical leakagecould be dangerous. In the case of a toothbrush, water and toothpasteare commonly used on the brush and, when inserted in the mouth, a fairlygood electrically conducting path exists for any leakage current fromthe device. a

With an oscillating shaft, it is difiicult to achieve watertightness,while at the same time permitting oscillaious of sufiicient amplitude tobe obtained with the limited power available. Further, even thoughinitially obtained, over an extended period of use the watertightnessmay become impaired.

In devices of this type, an electric switch therein is convenient sothat the device can be turned 0E without unplugging the cord from theelectric outlet. Further, since it may be desired to start and stop thedevice during its use, as in applying dentifrice to the brush head, itis desirable for the switch actuating mechanism to be arranged forconvenient action by the fingers with the device held in the hand innormal operating position.

However, since a switch inherently involves the making and breaking ofan electric circuit, and hence movement of parts, great care must beexercised to preserve watertightness. Due to space limitations in adevice of this Patented May 4, 1%65 type, switch water-tightness isdifficult to attain while at the same time preserving convenience ofuse.

An electric toothbrush with an electric switch incorporating severalfeatures for providing watertightness is described in copendingapplication Serial No. 155,366, now Patent No. 3,112,416, filed November28, 1961 by Moret for Electrically-Operated Hand Appliances for CorporalCare, particularly Toothbrushes. In the spe cific embodiment theredescribed the switch contacts are mounted in a fitting in the casing andcovered by a watertight elastic member. A slider is mounted on thefitting for movement transversely of the casing. A pin mounted forlongitudinal movement of the fitting is engaged by an inclined surfaceof the slider and presses against the elastic covering to move oneswitch contact relative to the other. A pair of resilient areas in theeasing on opposite sides of the shaft near respective ends or" theslider enable transverse movement of the slider in cit-her direction bymanual pressure on respective resilient areas, thereby enabling theswitch contacts to be opened and closed.

The present invention is an improvement on that or" the aforesaidapplication, and avoids the use of an elastic coveringagainst which apin is pressed, thereby avoiding the possibility of eventual wear ordeterioration of the elastic covering which would impair watertightness.The present invention provides a switch structure which is normallywatertight, but which is so designed that if, through wear during use,deterioration with time, or errors in assembly, etc. watertightness isimpaired, the amount of leakage current which can flow is so small asnot to endanger the user. To this end, certain switch elements areassembled and cooperate with one another with clearances that aresufliciently small so that the resistance of a liquid path between theelements will be suficient to prevent any current flow which would bedangerous to the user.

As specifically described hereinafter, the switch contacts are mountedin a chamber of a fitting of insulating material which is completelyclosed except for a small aperture Whose length is large compared to itsdiameter. A pin of insulating material fits into the aperture with avery small clearance, and the head of the pin is actuated by a slider toopen and close the switch contacts. Sealing means are provided betweenthe pin and surrounding walls near the head thereof, so as to normallyprevent water, toothpaste and the like from entering the switch contactchamber. 'I-lowever, the diameter, length and FIG. 1 is an overall viewof an electrically-operated toothbrush including a handle and anattached sternbrush;

FIGS. .2 and 3 are longitudinal views of the handle, taken at rightangles to each other, with the upper portion of the casing cut away;

FIG. 4 is a fragmentary longitudinal section through the portion of thecasing containing the switch mechanism, in a plane at right angles tothat of FIG. 3;

FIG. 5 is a transverse cross-section taken along line 55 of FIG. 4;

FIG. 6 is a transverse cross-section taken along line 6d of FIG. 4; and

FIG. 7 is a cross-section taken along arcuate line 77 of FIG. 5.

Referring to FIG. 1, a casing .10 forms a handle, and shaftend 11'holding a brush head projects from the front end thereof. In thisembodiment the brush head is detachable from the handle and comprises astem 12 with bristles 13 mounted thereon, with a coupling 14 enablingthe brush stem to be. conveniently attached and removed.

The casingis preferably made of an insulating material such as aplastic, and resilient areas, i.e. buttons 15, 15', are provided foractuating the internal switch mechanism. Alternating current from anexternal power source is supplied through an insulated,multiple-conductor electric cord 16 extending through a reinforcement 17in the end cap 10 of the casing, all secured together in watertightrelationship.

Referring to FIGS. 2, 3 and 4 the electrical means shown for oscillatingshaft 11 may be a motor of the type shown in the aforesaid Patent2,917,758. The stator of the motor includes a pair of longitudinallyextending pole pieces 21, 21 with a coil (not shown) to which A.-C.current is supplied from line 16 for producing magnetic flux in the gapbetween the ends of the pole pieces.

A rotor 22 mounted on shaft 11 is located between the front ends of polepieces 21,21. Shaft 11 is rotatably mounted in bearing plate 23* and anaxial hole in fitting 24. of insulating material. The bearing plate 23is attached to the pole pieces 21, 21' and an annular surface 25 offitting 24 is likewise attached to the pole pieces. The rotor 22includes a permanent magnet which interacts withthe alternating magneticflux between adjacent portions of pole pieces 21, 21' to producerotational oscillation. Springs 26, 26 are each secured at one end tothe shaft 11, and the other ends are fixed in fitting 24 so as toprovide spring biasing which returns the shaft 11 to its mean positionof equilibrium after each oscillation imparted to it in one direction orthe other.

This type of motor is described in detail in the aforesaid Patent2,917,758, and further description here .is

unnecessary.

To prevent the entry of water, etc. into the portion of the casingcontaining the. motor and electric switch, a flaring sleeve 31 ofresilient, water-impermeable material is provided. The front end 32thereof encircles an enlarged section 18 of shaft endll'inwatertightrela tionship, and the rear end is pressed against theinside of casing 10 by an annular section 27 of fitting 24. As shown inFIG. 4, the shaft end 11 is a molded section of plastic material fittingover and attached to shaft 11 by a steelpin 19. Waterproofing sleeves ofthis type are described in Patent No. 3,060,474,.issued October 10,1962,to Woog, and in copending application Serial No. 221,258, filedSeptember 4, 1962,by Robert Simmen. The flexibility of the sleeve allowsrotational oscillation of the shaft without impairing the watertightconnections with shaft and casing. This, together with the watertightcasing rearward of the sleeve, normally prevents entry of water, etc. tothe motor compartment.

Describing now the electric switch of the present invention, a slider 41is mounted inthe fitting 24 and arranged to be pushed in eitherdirection by buttons 15, 15'. The slider is arranged to actuate a pin 42of insulating material which fits into an aperture 43 in therfitting 24and engages a flexible contact blade 44 to move it toward acorresponding fixed contact. r 7

Considering first the slider 41, this is bestshown in FIG. 5. The slidermay be of insulating material and has a cutout 45 which fits around arounded post section 46 of the fitting 24. As shown, the cutout 45 isofgenerally trapezoidal form. In moving frornone position to the other,the slider pivots around post section 46.

A raised section 48 of portion of the fitting 24 so as to provideadditional guidance along the arcuate path.

As shown in FIG. 7, the slider is recessed along a por tion of its lowerface at 49 and this face is provided with two laterally-extendinggrooves 51 and 52 of diiferent depths. These grooves are shaped toaccommodate the head 42' of pin42. Withthe slider 41 inthe positionshown in FIG. 7, the head of the pin is in the deeper groovecorresponding to the open switch position. With the slider moved to theright as seen in FIG. 7, by pressing button 15 (FIG. 5), the shallowergroove 52rwill engage the head, corresponding to the closed switchposition.

The switch contact arrangement is best shown in FIGS. 4 and 6. Anannular insulating support 53 fits into an annular recess in fitting 24around a neck portion 54 of the fitting. The flexible contact blade 44is fixedly attached to support 53 at 55, an insulating stub 53' onsupport 53 assisting in initial orientation of the blade. A fixedcontact 56 is also mounted on support 53 beneath the free end of theflexible blade, as seen in FIG. 6.

The flexible blade 44 extends around the neck portion 54 of the fitting24, and pin 42 engages it in the region indicated at 57. Downwardmovement of the pin 42, as seen in FIG. 4, presses the end of theflexible blade 44 against the fixed contact 56 to close the switch. Whenthe leads have been attached to the blade and fixed contact, the support53 is sealed in the fitting by a plug 58 of insulating plastic material.Thus, the switch contacts are in a chamber of insulating fitting 24which is completely sealed except for the aperture 43 in which the pin42 is mounted.

The pin 42 is 'made fluid-tight with the fitting 24 by means of aresilient washer 59 which is force-fitted around the upper portion ofthe pin, just below the head 42', and also force-fitted against the wall61 of a hole 62 in the fitting 24 leading to the smaller diameteraperture 43. The lower end 61' of the hole 61 is tapered to restrictdownward movement of washer 59. Also, the pin 42 is provided with atapered section 42". Thus, when the pin 42 is pressed downward, as seenin FIG. 7, the washer 59 bends "but maintains a fluid-tight seal. Thehead 42' of the pin advantageously forms a close fit in the upper end ofhole 61.

The switch contact members 44 and .56 are connected in series with themotor coil and the cord 16; To this end, lead 63 (FIG. 3) is placed in aslot in pole piece 21 and connected to the flexible blade 44. Anotherlead (not shown) lies in a similar slot in the other pole piece 21 andis connected to the fixed contact 56. i

'It will be observed that with proper assembly the switch contactmembers are protected from the entry of water, etc. by the sealingthereof in fitting 24 and the sealing of the pin 43 in the fitting bywasher 59. Additionally, the flexible sleeve 31 prevents entry of water.In use, it is possiblethat eventually the sleeve 31 will fail topreserve watertightness through deterioration, chemical action, etc. Thesame is true of washer 59. In case of such deterioration, or in casewasher 59 is inadvertently omitted during assembly, water, or a mixtureof water with toothpaste, etc., could reach the pin 42 and eventuallyenter the chamber containing the switch contacts.

As a further factor on safety, the pin 42 and aperture 43 are ofsufiiciently small diameter compared to the length of the aperture, andthe clearance therebetween is suificiently small, so that the smallcross-section and length of the tube of liquid capable of forming in'the clearance space provides a high resistance sulficient to limit thecurrent to a safe value. The resistance under such circumstances may bedetermined by the application of Ohms law, according to the formula:

where R is the resistance, l is the length of the path along aperture43, s is the cross-sectional. area of the clearance between'pin 42 andaperture 43, and its the specific resistivity of any liquid encounteredin'use. In one par ticular embodiment, wherein the diameter-of thepin'was about 1 millimeter, the diameter of the aperture was just 5 to5.5 milliampe'res at 200 volts and about 3 to 4.5 milli- V arnperes at100 volts.

ohms. Thus, under the most, unfavorable conditions, the leakage currentis not high enough to endanger the user, and will commonly result inonly a slight tingling The invention has been described in connectionwith a specific embodiment thereof showing a preferred arrangement. Itwill be understood that. modifications and changes in detail may be madeby those skilledin the art within the spirit and scope of theinvention.

I claim: j,

-1. An electrically-operated hand appliance for corporal care whichcomprises 7 (a) an elongated casing forming a handle,

(b) a shaft extending to the exterior at one end of the casing forcarrying an appliance head,

(c) electrical means mounted Within the casing for driving the shaft andmeans for supplying electric power thereto,

(d) a fitting of insulating material fixedly mounted in the casing,

(e) a slider mounted on said fitting for movement transversely of thecasing with at least one end thereof adjacent the casing and having asurface inclined to the direction of movement thereof,

(1) at least .one resilient area on the casing near said end of theslider for enabling transverse movement of the slider by manual pressurethereon,

(g) a pair of cooperating, relatively movable switch contact membersmounted within a chamber in said fitting and connected in the powersupply circuit to said electrical means, a

(12) at least one of said switch contact members being flexible,

(i) a longitudinally-extending elongated aperture of small crosssect-ionin said fitting communicating with said chamber,

(i) said chamber being insulatedly closed except for said aperture,

(k) a pin of insulating material in said aperture for engagingsaid-flexible switch contact member,

(I) said pin being positioned for engagement by the inclined surface ofthe slider to move the pin longitudinally thereof and thereby move theflexible switch contact member to and away from the other contactmember,

(m) and a resilient sealing member near the end of said pin adjacent theslider in sealing contact with said pin and said fitting.

2. An appliance in accordance with claim 1 in which the length anddiameter of said aperture and the clearance of the portion of theinsulating pin therein are predetermined to yield a high resistance inthe presence of liquid that may leak thereinto during use and limit anyleakage current to a low value. i

3. An electrically-operated hand appliance for corporal care whichcomprises (a) an elongated casing forming ahandle,

(b) a shaft extending to the exterior at one end of the casing forcarrying an appliance head, i

(c) electrical means mounted within the casing for driving the shaft andmeans for supplying electric power thereto,

(d) a fitting of insulating material fixedly mounted in the casing,

(e) a slider mounted on said fitting for movement transversely of theca-sing'with at least one end The corresponding resistances may becalculated to be in the range of20,000 to 40,000

6 thereof adjacent the casing and havinga surface inclined to thedirection of movement" thereof, .(f) at leastone resilient area on' thecasing-nearsaid end of the slider for enabling transverse movement erthe slider byma'nual pressure thereon, a '(g) apairrof lcooperating,relatively movable switch contact members mounted Within achamber insaid fitting andtconnected in the power supply circuit to saidelectrical means, a (h) atleast one of said switch contact members beingflexible, a

i *(z') a longitudinally-extending aperture in, said fitting extendingfrom said chamber toward said slider,

-(j) said aperture having a portion adjacent the chamber of smallcross-section and length large compared 'to the diameter thereof and aportion toward the slider of larger diameter, j I

(k) said chamber being insulated-1y closed except for 1 lsaidaperture,

' (l) a pin of nsulating material closely fitting in the smallcross-sectional portion of said aperture for engaging said flexibleswitch contact member and having a head of larger cross-section forengaging said slider,

(m) said pin being movable longitudinally bythe in-.

olined surface of the slider to rnove the flexible switch contact memberto and away from the other contact member,

(n) and a resilient sealing washer encircling said pin below the headthereof in sealing relationship and tightly engaging the larger diameterwall section of said aperture in sealing relationship.

4. An appliance in accordance with claim 3 in which said resilientsealing washer is substantially rforce-fitted on said pin and in saidaperture, and the space between the washer and the small diameterportion of the aperture is predetermined to accommodate flexing of thewasher over the range of movement of the pin.

5. An appliance in accordance with claim 3 in which said pin has anoutwardly tapered section engaging the center of said resilientwasher onthe pin head side thereof and the wall section of the aperture has aninwardly tapered section engaging the periphery of the washer on theother side thereof, the space between the washer and the small diameterportion of the aperture being predetermined to accommodate flexing ofthe washer over the range of movement of the pin.

6. An electrically-operated toothbrush which comprises (a) an elonagtedcasing forming a handle,

(12) a shaft extending to the exterior at one end of the casing forcarrying a toothbrush head,

(c) electrical means mounted within the casing for driving the shaft,

(d) means for supplying power to said electrical means from a powermain,

(e) a fitting of insulating material fixedly mounted in the casing, a

(f) a slider mounted on said fitting for movement transversely of thecasing with at least one end thereof adjacent the casing and having asurface inclined to the direction of movement thereof,

(g) at least one resilient area on the casing near said end ofthe sliderfor enabling transverse movement of the slider by manual pressurethereon,

'(h) a pair of cooperating, relatively movable switch contact membersmounted Within a chamber in said fitting and connected in the powersupply circuit to said electrical means,

(i) at least one of said switch contact members being flexible,

(i) a longitudinally-extending aperture in said fitting extending fromsaid chamber toward said slider,

(k) said aperture having a portion adjacent the chamber of smallcross-section and length large compared to the diameter thereof :and aportion toward the slider of larger diameter,

*(I) said chamber being insu-latedly closedexcept-for said aperture, (m)a pin of insulating material closely fitting in the smallcross-sectional portion of said aperture for engaging said flexibleswitch contact member and having'a head of larger. cross-section forengaging said slider,

(71) said pin being movable longitudinally by theiin-.

dined sunfiaee of the slider to move the flexible switch contact memberto and away from the other contact member,

(o) and a resilient sealing washer'eneireling said pin below the headthereof in sealing relationship and tightly engaging the larger diameterwall section'of said aperture in sealing relationship,

7 (17) said pin having an outwardly tapered section engaging the'centerof said resilient washer on the pin head side thereof and the wallsection of the aperture having an inwardly tapered section engagwithclaim 6 in which the length and diameter of thesmall cross-sectionportion of said aperture andthe clear-' ance. of the portion of, theinsulating pin therein are predetermined to yield a high resistance inthe presence of liquid that may leak therein'to during use and limit anyleakage current to alow value.

References Cited by the Examiner UNITED STATES PATENTS 2,442,164 5/48Ferris 200-457 2,532,000 111/50 West. 2,677,730 5/54 Weidenman 200-1573,112,416 11/63 Moret 1522X CHARLES A. WILLMUTH, Primary Examiner.

1. AN ELECTRICALLY-OPERATED HAND APPLIANCE FOR CORPORAL CARE WHICHCOMPRISES (A) AN ELONGATED CASING FORMING A HANDLE, (B) A SHAFTEXTENDING TO THE EXTERIOR AT ONE END OF THE CASING FOR CARRYIONG ANAPPLIANCE HEAD, (E) ELECTRICAL MEANS MOUNTED WITHIN THE CASING FORDRIVING THE SHAFT AND MEANS FOR SUPPLYING ELECTRIC POWER THERETO, (D) AFITTING OF INSULATING MATERIAL FIXEDLY MOUNTED IN THE CASING, (E) ASLIDER MOUNTED ON SAID FITTING FOR MOVEMENT TRANSVERSELY OF THE CASINGWITH AT LEAST ONE END THEREOF ADJACENT THE CASING AND HAVING A SURFACEINCLINED TO THE DIRECTION OF MOVEMENT THEREOF, (F) AT LEAST ONERESILIENT AREA ON THE CASING NEAR SAID END OF THE SLIDER FOR ENABLINGTRANSVERSE MOVEMENT OF THE SLIDER BY MANUAL PRESSURE THEREON, (G) A PAIROF COOPERATING, RELATIVELY MOVABLE SWITCH CONTACT MEMBERS MOUNTED WITHINA CHAMBER IN SAID FITTING AND CONNECTED IN THE POWER SUPPLY CURCUIT TOSAID ELECTRICAL MEANS, (H) AT LEAST ONE OF SAID SWITCH CONTACT MEMBERSBEING FLEXIBLE, (I) A LONGITUDINALLY-EXTENDING ELONGATED APERTURE OFSMALL CROSS-SECTION IN SAID FITTING COMMUNICATING WITH SAID CHAMBER, (J)SAID CHAMBER BEING INSULATEDLY CLOSED EXCEPT FOR SAID APERTURE, (K) APIN OF INSULATING MATERIAL IN SAID APERTURE FOR ENGAGING SAID FLEXIBLESWITCH CONTACT MEMBER. (L) SAID PIN BEING POSITIONED FOR ENGAGEMENT BYTHE INCLINED SURFACE OF THE SLIDER TO MOVE THE PIN LONGITUDINALLYTHEREOF AND THEREBY MOVE THE FLEXIBLE SWITCH CONTACT MEMBER TO AND AWAYFROM THE OTHER CONTACT MEMBER, (M) AND A RESILIENT SEALING MEMBER NEARTHE END OF SAID PIN ADJACENT THE SLIDER IN SEALING CONTACT WITH SAID PINAND SAID FITTING.